The purpose of this project is to investigate the cellular events which take place in excitation-contraction coupling in smooth muscle. Currently, we are determining if there are significant changes in the level of phosphorylation of other myoepithelial proteins in response to oxytocin. We also wish to test oxytocin analogues and other smooth muscle stimulants, e.g., norepinephrine, for their effect on the phosyphorylation of the LC20 using the above labelling procedure. We intend to investigate further the involvement of Ca2 ion in the phosphorylation of the LC20. We would like to determine whether there is degradation of the oxytocin during the incubation as this would affect the determination of the minimum oxytocin dose to effect a response. We will also investigate lowering of the incubation temperture which could result in "slippage" of the excitation-contraction coupling mechanism, i.e., at lower temperature oxytocin can still bind to its membrane receptor while smooth muscle cannot contract.